Reeves was one of the big country stars of the 1950's and 1960's. He had a mellow, soothing sound, and was universally known as "Gentleman Jim Reeves." So in a sense this might be idiomatic-like in certain usages, for example:
His voice is as mellow as an old Jim Reeves tune.
He's an old-style gentleman, makes you think of a Jim Reeves tune.